The heart is the center of a person's circulatory system and includes an intrinsic electro-mechanical system for performing pumping functions. The left portions of the heart, including a left atrium (LA) and a left ventricle (LV), draw oxygenated blood from the lungs and pump it to body organs to provide the organs with their metabolic need for oxygen. The right portions of the heart, including a right atrium (RA) and a right ventricle (RV), draw deoxygenated blood from the body organs and pump it to lungs where the blood gets oxygenated. The myocardium of the heart contracts in a coordinated fashion to provide these pumping functions. In a normal heart, a sinoatrial (SA) node, the heart's natural pacemaker, generates intrinsic electrical pulses that propagate through an electrical conduction system of conductile cardiomyocytes to various regions of the heart to excite the contractile myocardial syncytium of the cardiac muscle. For example, intrinsic electrical pulses originating from the SA node propagate through an atrioventricular (AV) node that is in the interatrial membranous septum between the RA and LA. From the AV node, a specialized intrinsic conduction system is used by the electrical impulses to reach ventricular myocardial tissues, resulting in contraction activities of ventricles. This specialized conduction system includes the His bundle, the right and left conduction bundle branches that extend along the septum between the RV and LV, and the Purkinje fibers that contact the ventricular myocardial tissues. Coordinated delays of the propagations of the intrinsic electrical pulses in a normal electrical conduction system cause the various portions of the heart to contract in synchrony which results in efficient pumping functions. In addition, electrically conductile devices chronically placed in the right ventricular cavity may support endomyocardial trabecular growth which may contribute to an increase in cardiomyocyte mass and pumping function. In an example, the conductile devices may be placed in the right or left ventricular cavity to support endomyocardial trabecular growth.
Heart disease may damage cardiac tissue, resulting in a loss of contractile and conductile myocardial cells and thus an inefficient pumping function, which may lead to further cardiac tissue damage and reduced cardiac output. An electrical pacing therapy, such as cardiac resynchronization therapy (CRT) may be provided to compensate for the damaged cardiac tissue by providing electrical pulses to the heart. However, there remains a need to restore damaged cardiac tissue.